Frequency changing inductance system



April 26, 1932. L. A. GEBHARD 1,855,392

FREQUENCY CHANGING iNDUCTANGE SYSTEM Filed March 13, 1931 2 Sheets-Sheet l I: Ea-l INVENTOR.

(104420 a gme'izowd,

BY W/(M ATTORNEY I .April 26, 1932.

L. A. GEBHARD FREQUENCY CHANGING INDUCTANCE SYSTEM Filed March 13, 1951 2 Sheets-Sheet 2 Cami/a a.

BY W ATTORNEY Patented Apr. 26, 1932 UNITED STATES PATENT OFFICE LOUIS A. GEBHARD, OF WASHINGTON, DISTRICT OF COLUMBIA, ASBIGNOB TO WIRED RADIO, INC., 01 NEW YORK, N. Y., A CORPORATION OF DELAWARE FREQUENCY CHANGING INDUCTANCE SYSTEM Application filed March 13, 1831.

My invention relates broadly to high frequency signaling systems and more particularly to a frequency changing system for high fre uency signaling apparatus.

One of the objects of my invention is to rovide a construction of switch apparatus or shifting the operating characteristics of a high frequency signaling circult from one frequency to another.

Another object of my invention 1s to provide a construction of switching mechanism for high frequency signaling systems by which a change in the effective inductance of a signaling system may be rapidly efiected, and with substantiall no loss during operation.

Still another ject of my invention is to provide an arrangement of switching mechanism shiftable in position from one 1nductance to another for effectively including a selected amount of inductance in a h gh frequency signaling circuit while maintaining the leads extremely short.

A further object of my invention is to provide a construction of frequency changing switch having a chain and sprocket actuating mechanism for moving a multiplicity of contactors along a bus system for selectively establishing connection with induc- 4 tance units of differing inductance values with minimum length of leads for securing maximum etficiency in a transmission systern.

Other and further objects of my invention reside in the construction of switch mechanism for a high frequency inductance system as set forth more fully in the specification hereinafter following by reference to the accompanying drawings, in which:

Figure 1 is a rear elevation with parts broken away and in section, showing a multiplicity of inductance units and the switching means of my invention for selectively ineluding inductances of selected value in the signaling circuit; Fig. 2 is atransverse vertical cross-sectional view of the'inductance system on line 2-2 of Figs. 1 and 3; Fig. 3 is a plan view partially in section of the apparatus shown in Fig. 1; Fig. 4 is a detailed view showing the interlock mechanism for maintaining the switching members in con- Serial No. 522,498.

tact with a selected inductance unit; and Fig. 5 is a front view of the anel of the transmitter showing the in icator projectible therethrough by which the operator is advised of the particular inductance which is effective in the transmitting circuit. 7

In a radio transmitter covering a wide frequency band it is necessary to change the inductance in the various circuits at various points in the band. In high frequency transmitters it is essential that the connections between the coils and the associated circuits bevery short in order to reduce losses to the minimum as well as to permit tuning to the required frequency. It is also desirable to change frequency quickly. These features are incorporated in the construction of my invention.

In the accompanying drawings, reference characters 1, 2, 3 and 4 indicate the inductance coils. These inductance coils are mounted on longitudinal insulated members 1a, 2a, 3a and 4a. The coils are prevented from turning on the longitudinal members by means of clamps 5. Coils 1, 2, 3 and 4 carr contacts 16, 2b, 3b and 4b, which engage with brushes 6 mounted on insulating member 7 which is made to move at right angles to the coil and thus engage the particular coil desired. Brushes 6 also connect to bars 8 which are mounted on insulating members 9 and 10. These insulating members are supported in turn from the frame work of the transmitting set which is shown at 11 and 12. The connections to the external circuits are made through binding posts 13 which connect to bars 8. The longitudinal members which support the coils are in turn supported by members 14 and 15 from the frame work of the transmitter. Insulating member 7 which supports brushes 6 is caused to move in'a direction parallel to the axes of the coils by means of chains, trained over sprockets operated by a crank 29?). This crank turns shaft 16 carrying sprockets 17 and 17a. The teeth of these sprockets engage with the chains 18 and 18a which pass over similar sprockets 19, 19a on shaft 32, 20, 20a on shaft 33, and 22 and 21a on shaft 34. The chains are connected to insulating cross member 7 which carries brushes 6. The ends of part 7 are arranged to slide on rods 22 and 22a which are mounted perpendicular to the axes of the coils. A pointer 23 is mounted on part 7 and projects through a slot 35 in the front panel 2- of the radio transmitter. This is shown more clearly in Fig. 5, the various numerals indicating the particular coil connected in the circuit. The mechanism which holds the coils in engagement at the proper point is shown at Fig. 4. Rod 22 has cut in its surface indentations 31, 31a, etc. corresponding to the positions at which the brush 6 is to be brought to rest. Into these indentations a pin 25 is forced by means of spring 26. The spring and pin are held in place by cap 27 which screws on the part 28 which in turn slides over rod 22. Two of these mechanisms are placed at 29 and 29a as shown in Fig. 3. Counterweights 30 and 30a are provided so as to balance the weight of members 6 and 7 The bus bars 8 establish connection with the other parts of the transmitting apparatus providing an efficient means of completing the circuits from the different inductance units through the switching members 6. Each of the switching members 6 is provided with spring jaws tending to forcefully grip opposite sides of the contact blades on the inductance units and the bus bars 8 for insuring a good electrical connection. The balanced arrangement of the mechanism which carries the switching members 6 is such that very little force must be applied at the crank 29?) to rotate shaft 16 for shifting the switching mechanism from one interlocked position to another interlocked position for correspondingly effecting a change in the particular inductance unit which is connected in the high frequency signaling circuit.

While I have described my invention in one of its preferred embodiments, I desire that it be understood that modifications may be made and that no limitations upon my invention are intended other than are imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In an inductance system, a multiplicity of inductance units of different frequency characteristics, contact clips projecting from each of said inductance units in alignment one with respect to another, a switch operating mechanism, a set of bus bars extending adjacent said inductance units in alignment with the contact clips projecting from said inductance units, switch blades extending between said bus bars and said contact clips and connections between said switch operating mechanism and said switch blades for shifting said switch blades from one position to another for selectively establishing connection with a particular inductance unit. a

2. A frequency selection'apparatus comprising a supporting frame, a multiplicity of inductance units carried by said supporting frame, each of said inductance units having laterally projecting contact clips thereon, a multiplicity of vertically extending bus bars aligned with the contact clips on said inductance units, an insulated carrier movable between said bus bars and the contact clips on said inductance units, and means for shifting said switch blades from one position along said bus bars to another position along said bus bars for selectively establishing connection with a particular inductance unit.

3. Frequency adjusting means comprising a frame, a multiplicity of inductance units each having different frequency characteristics arranged in vertical alignment on said frame, contact clips horizontally projecting from each of said inductance units, a multiplicity of vertically extending bus bars spaced from said contact clips, an insulated carriage disposed between said bus bars and said contact clips, a plurality of switch blades disposed on said insulated carriage and adapted to bridge the gap between said bus bars and said contact clips, and means for selectively shifting said switch blades from one inductance unit to another inductance unit for effectively establishing connection with a particular inductance unit.

4. Frequency adjusting means comprising a frame structure, a multiplicity of inductance units of differing frequency characteristics aligned in the same plane on said frame, contact clips projecting from each of said inductance units, a plurality of bus bars extending parallel to said inductance units and aligned with the contact strips on said inductance units, an insulated carriage disposed between said contact clips and said bus bars, a plurality of brushes disposed on said carriage and adapted to establish wiping contact between said bus bars and the contacts on said inductance units, and means for shifting said carriage along said bus bars for selectively establishing connections with a particular inductance unit.

5. Frequency adjusting means comprising a frame structure, a multiplicity of inductance units of differing frequency characteristics aligned in the same plane on said frame, contact clips projecting from each of said inductance units, a plurality of bus bars extending parallel to said inductance units and aligned with the contact strips on said inductance units, an insulated carriage disposed between said contact clips and said us bars, a plurality of brushes disposed on said carriage and adapted to establish wi ing contact between said bus bars and tfie contacts on said inductance units, and a chain and sprocket mechanism for shifting said carriage to selected positions along said bus bars forbringing said brushes into registra tion with the contact clips on said inductance units.

6. Frequency adjusting means comprising a frame structure, a multiplicity of inductance units of differing frequency characteristics aligned in the same plane on said frame, contact clips projecting from each of said inductance units, a plurality of bus bars extending parallel to said inductance units and aligned with the contact strips on said inductance units, an insulated carriage disposed between said contact clips and said bus bars, a plurality of brushes disposed on said carriage and adapted to establish wiping contact between said bus bars and the contacts on said inductance units, a plurality of shaft members extending parallel to the axes of said inductance units, sprockets carried by said shaft members, a pair of chains operative over said sprockets, said chains being connected to said carriage and means external to said frame for operating one of said shafts for impartin movement to said sprockets and driving said chains and shifting said carriage with respect to said bus bars for selectively establishing connection with a particular inductance unit.

7. Frequency adjusting means comprising a frame structure, a multiplicity of inductance units of differing frequency characteristics aligned in the same plane on said frame, contact clips projecting from each of said inductance units, a plurality of bus bars extendin parallel to said inductance units and aligned with the contact strips on said inductance units, an insulated carriage disposed between said contact clips and said bus bars, a plurality of brushes disposed on said carriage and adapted to establish wiping contact between said bus bars and the contacts on said inductance units, a control mechanism for shifting said carriage along said inductance units, and means for selectively locking said control mechanism in position adjacent any one of said inductance units for maintaining an electrical connection between said bus bars and a particular inductance unit.

8. Frequency adjusting means comprising a frame structure, a multiplicity of inductance units of differing frequency characteristics aligned in the same plane on said frame, contact clips projecting from each of said inductance units, a plurality of bus bars extending parallel to said inductance units and aligned with the contact strips on said inductance units, an insulated carriage disposed between said contact clips and said bus bars, a plurality of brushes disposed on said carriage and adapted to establish wiping contact between said bus bars and the contacts on said inductance units, control mechanism for displacing said carriage to connection therewith.

LOUIS A. GEBHARD. 

